Switch enclosure with sealing means operable by switch-operating

ABSTRACT

The switch enclosure comprises a box within which a switchoperating mechanism is mounted. An external operating handle is operable to cause the mechanism to move to ON and OFF switch positions. The box is closed by a hinged door, and a sealing gasket is provided between the door and box. A combined sealing and latching bar in the box is arranged to draw the door into, and hold it in, closed sealing engagement. The invention is characterized in that a ratchet connection is provided between the switch-operating mechanism and the bar for moving the bar into sealing and latching position when the handle is operated to move the switch-operating mechanism a predetermined distance toward ON position and to release the mechanism from the bar, and permit return of the mechanism to OFF position by the handle, while the bar remains in sealing and latching position. An interlock on the door latches the bar in the sealing and latching position upon movement of the bar into said position by the mechanism.

United States Patent [72] Inventor Tadeuszl. Rys Lexington, Ky. [21] Appl. No. 811,392 [22] Filed Oct. 16, 1970 [45] Patented Dec. 21,1971 [73] Assignee Square D Company Park Ridge, Mich.

[54] SWITCH ENCLOSURE WITH SEALING MEANS OPERABLE BY SWITCH-OPERATING 6 Claims, 11 Drawing Figs.

[52] U.S.Cl 200/168 G, 200/50 A. 3 l 7/120 [51] Int. Cl "01h 9/04, H0 l h 9/06 [50] Field of Search 200/50 A, l68 G, 168 A;3l7/l I2, I20

[56] References Cited UNITED STATES PATENTS 3,059,072 l0/l962 Mekelburg 200/50 A 3,38l,l06 4/1968 Rys ZOO/168G 3,378,666 4/1968 Rys ABSTRACT: The switch enclosure comprises a box within which a switch-operating mechanism is mounted. An external operating handle is operable to cause the mechanism to move to ON and OFF switch positions. The box is closed by a hinged door, and a sealing gasket is provided between the door and box. A combined sealing and latching bar in the box is arranged to draw the door into. and hold it in, closed sealing engagement.

The invention is characterized in that a ratchet connection is provided between the switch-operating mechanism and the bar for moving the bar into sealing and latching position when the handle is operated to move the switch-operating mechanism a predetermined distance toward ON position and to release the mechanism from the bar, and permit return of the mechanism to OFF position by the handle, while the bar remains in sealing and latching position. An interlock on the door latches the bar in the sealing and latching position upon movement of the bar into said position by the mechanism.

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SWITCH ENCLOSURE WITH SEALING MEANS OPERABLE BY SWITCH-OPERATING This invention relates to a switch enclosure in the form of a box having a service opening and a door hinged to the box for closing the opening. A sealing gasket is interposed between the door and box in surrounding relation to the opening and arranged so that when the door is drawn tightly into final closed position, a dust and weatherproof seal is provided to prevent ingress of foreign matter, moisture, and the like between the door and box.

A switch-operating mechanism within the box is operable by an external operating handle so that the mechanism is caused to move selectively to OFF and ON positions wherein it opens and closes the switch, respectively.

A door sealing and latching device within the box is arranged to be operated by the mechanism to latch and seal the door when the mechanism is moved part way toward ON position and to be released from operation by the mechanism; upon continued movement of the mechanism to ON position and also upon return of the mechanism to OFF position while the latching and sealing device remains in a position for holding the door closed and sealed. The device also includes means cooperable with an interlock on the door for latching the the device in door latching and sealing position. The mechanism and device are connected by a ratchet driving connection which is operative to drive the device to its latching and sealing position.

Defeaters are provided for the interlocks, and each has a part exposed for access at the exterior of the box by a tool so that the interlocks can be defeated to permit release and unsealing of the door for opening while the switch-operating mechanism and switch are in their ON positions.

Aside from the specific 'manner of operating the door latching and sealing device, through the switch-operating mechanism, by the external switch-operating handle, the structure is essentially the same as disclosed in my US. Pat. No. 3,378,666, issued Apr. 16, 1968, and entitled Switch Enclosure with Multiple Interlocks, and US. Pat. No. 3,381,106, issued Apr. 30, I968, and entitled Switch Enclosure and Sealing Means Therefore.

The present invention distinguishes from the structures disclosed in the above patents primarily by the fact that they require, in addition to an external switch-operating handle, a separate external handle for operating the switch sealing and latching device, whereas, in the present invention, the operation of this device is effected by the same external switchoperating handle which operates the switch-operating mechanism.

Various specific objects and advantages of the invention will become apparent from the following description wherein reference is made to the drawings, in which:

FIG. 1 is a front elevation of a switch enclosure of the present invention, showing the switch-operating handle in ON position;

FIG. 2 is a right side elevation of the structure illustrated in FIG. 1, a portion of the door and box being broken away for cleamess in illustration;

FIG. 3 is a fragmentary sectional view of a portion of the right-hand side of the structure illustrated in FIG. 1, taken on lines 3--3 in FIGS. 1 and 2;

FIG. 4 is a view similar to FIG. 2 but showing the switchoperating handle in the OFF position;

FIG. 5 is a fragmentary sectional view through the switchoperating handle and associated parts and is taken on line 5- 5 of FIG. 4;

FIG. 6 is a fragmentary front elevation showing the latch bar for the door, door interlocks, the cam, and the cam operator, of the switch-operating mechanism, just prior to effecting driving engagement of the mechanism and bar by the ratchet drive connection;

FIG. 7 is a left side elevation of the structure illustrated in FIG. 6, parts thereof being broken away for clearness in illustration;

FIG. 8 is a view similar to FIG. 6 showing the same parts just prior to release of the switch-operating mechanism from the latching bar;

FIG. 9 is a left side elevation of the structure illustrated in FIG. 8;

FIG. 10 is a view similar to FIG. 6 showing the manner in which the ratchet connection permits return of the switchoperating mechanism to OFF position while the latching and sealing bar is in inoperative door release position; and

FIG. 11 is a left side elevation of the structure illustrated in FIG. 10.

Referring to the drawings, the switch enclosure comprises a sheet metal box 1 having side and rear walls, and an open front face with a peripheral edge 2. A door 3 is hingedly connected to one sidewall of the box for swinging freely into and out of closed position.

As mentioned in the above patents, it is desirable not only that the door be closed and latched in closed position, but that an effective seal be provided between the peripheral margin of the door and the aligned peripheral edge 2 of the box. For this purpose, a resilient gasket 4 is mounted on the margin of the inner face of the door in a position to be engaged and drawn tightly against the edge 2 of the box when the door 3 is in closed sealed position.

Mounted within the box is the usual rockable switch operating bar 5 which either carries a plurality of movable contacts or is otherwise connected to a switch within the box for driving the switch to ON and OFF positions, selectively. The bar is rockably supported at one end by a bracket 8, welded to one sidewall.

In order to operate the switch, an external switch-operating handle 10, comprising two laterally spaced and aligned metal arms 10a, is mounted on a suitable rock shaft 1 l. The shaft 11 extends through a suitable handle bearing 12 secured in fixed position on one side of the box.

The shaft 11 supports the handle portions 10a for rocking as a unit with the shaft relative to the bearing about the shaft axis. A cam operator 15 is mounted on, and for rocking with, the shaft 1 l. The cam operator carries at its outer margin a lug 17 which is arranged to engage and operate a cam 18 drivingly connected to the switch operating bar 5.

Since the cam 18 must be operated with lost motion relative to the handle 10, a lost motion connection is provided between the cam operator l5 and the cam 18. The cam comprises a plate mounted on the inner cylindrical end portion 19 of the shaft 11 for free rotation relative to the shaft 11. The plate has a pair of circumferentially spaced lugs 20 disposed on opposite sides of the adjacent bent over end portion 21 of the operating bar 5. The free end of the portion 21 is rotatably mounted in a bracket in coaxial relation to the mounting of the opposite free end of the bar 5 in the bracket 8.

The lug 17 on the cam operator 15 is operable in a slot 22 in the cam 18 and is of less extent circumferentially of the axis of the shah 19 than the slot 22. A suitable link 23 is pivotally connected at one end to the box and at the other end carries a pin 24 operable with a lost motion in a circumferential slot 25 in the cam 18. A dead center spring 26 is carried on the link 23 and is operative to drive the cam 18 to the open switch position when the cam 18 is moved by the handle 10 and operator 15 past dead center in the OFF or switch-opening direction, and to closed switch position when the cam 18 is moved by the handle 10 and cam operator 15 past dead center in the ON or switch-closing direction.

A lost motion connection between the cam operator 15 and the cam 18 is provided by suitable fingers 27 on the cam operator and aligned fingers 28 on the cam. A coil compression spring 29 embraces one finger of the cam 18 and one finger of the operator 15 at one end of the spring and the other finger of the cam 18 and other finger of the operator 15 at the opposite end of the spring. Thus by rocking the handle 10 clockwise in FIG. 2, the cam operator drives the cam 18 past dead center in the switch-closing direction and thereby the switch bar 5 is moved to swing the movable contacts of the switch to closed position with a snap action. Upon rocking the handle 10 in the opposite direction, the cam is operated to cause the switch bar to move with a snap action to the open position.

In order that the door be drawn tightly into sealed position when closed, the door is provided with an upper interlock plate 30 and a lower interlock plate 31. The upper plate 30 is rigidly secured to the inside of the door and has an upper wedge or sealing finger 32 and a lower interlock finger 33. The lower plate 31 has a wedge or sealing finger 34.

In order to seal the door in closed position with the switchoperating mechanism in ON switch position and so held, a sealing mechanism cooperating with the fingers 32 and 34 is operated.

The sealing mechanism comprises an interlock bar 39 which extends along the inner face of the sidewall of the box generally parallel to the plane of the door, and near the margin of the open face of the box. The bar 39 is secured in the box for movement endwise of the door along the adjacent sidewall of the box by means of suitable pins 40 disposed in elongated slots 41 in the bar so that the bar can be moved toward the upper end of the box and back toward the lower end of the box. The bar 39 is provided at its upper end with a wedge finger 42 and at its lower end with a wedge finger 43. When the bar is moved toward the upper end of the box the wedge finger 42 engages in camming relation with wedge finger 32 on the door, and the wedge finger 43 engages in camming relation with the wedge finger 34 on the door. The fingers 32 and 34 are sloped relative to the face of the door so that when so engaged by fingers 42 and 43 as the door interlock bar 39 is moved upwardly, they draw the door finnly toward the exposed forward edges of the sidewalls of the box and thus compress the gasket 4 sufficiently tightly against such edges for sealing the box.

A biasing compression spring 44 is arranged to bias the bar 39 to door releasing position.

As mentioned in the above-entitled patents, an external bar operating handle was provided for driving the bar 39 in the locking and sealing direction to final position. In the present invention no such bar operating handle is provided. Instead, a driving ratchet connection is provided between the external operating handle for the switch and the bar 39. This ratchet connection is arranged so that when the operating handle is moved a predetermined distance toward ON position, it positively drives the bar to the locking and sealing position against the force of the biasing spring 44 and then releases the bar so that the handle can continue toward ON position without further movement of the bar 39. The connection also permits return of the handle in the opposite direction to OFF position while the bar 39 is in either latching or releasing position.

This one-way ratchet mechanism is provided by means of a lug 45 on the cam operator l5, and a detent 46 on the bar 39. The detent 46 and lug 45 are arranged to provide a driving connection when the cam operator 15 is driven by the handle in the direction for driving the switch-operating mechanism to ON position, to release when the cam operator is moved in the opposite direction, and to pass each other without effecting a driving connection as the cam operator is moved to OFF position while the bar 39 is in unlatching position.

In the form illustrated, the movable part of the one-way ratchet connection is the detent 46 and it is mounted on the locking bar 39. As best illustrated in FIGS. 6 and 7, the detent is in the form of a leaf spring 46 secured by rivets 47 in fixed position on the bar 39 with the main body portion of the leaf spring in face to face juxtaposition with the inner face of the bar 39. The detent or spring 46 has a free end portion 48 facing downwardly or endwise of the bar in the unlatching direction of its movement. The free end portion slopes away from the face of the bar 39 on which it is mounted inwardly of the box or enclosure so that the free end is in the path of movement of the lug 45. Thus, when the cam operator 15 is driven by the handle 10 in the clockwise direction, as viewed in FIG. 2, which is the counterclockwise direction in FIG. 7,

the lug engages the free end 48 of the spring 46. The spring is sufficiently rigid, when so engaged and pushed upwardly by the lug 45, to overcome the forces of the biasing spring 44 and move the bar 39 to the latching position. The shape of the lower edge 50 of the spring 46 is such that upon continued clockwise rotation of the cam operator 15 toward the ON position, the lug 45 passes from the free end 48 of the spring 46 down along the edge 50 toward the back of the box so that there is a slight dwell of the lug and bar after the bar has been moved into latching and sealing position. Upon continued movement of the handle 10 to final position in the ON direction, the lug 45 passes the rear of the edge 50 and releases the detent 46 so that the bar 39 can be returned to unlatched starting position under the influence of the spring 44.

In order to latch the bar 39 in the cover sealing and locking position and hold it in said position until it is intentionally released, interlocks for the various operating mechanisms are provided.

The interlock for the sealing mechanism is mounted on the inside of the door 3 and arranged for movement into and out of engagement with the lower end of the interlock bar 39 when the bar 39 has been moved to door sealing and locking position by the handle 10. This interlock comprises a rocker which is pivotally connected by a pivot 56 to a suitable supporting boss 57 on the plate 31 at the inside of the door 3. The rocker 55 is biased to interlocking position by means of a compression spring 58. The rocker 55 has a bent over upper end 49 which, in the interlocking position, engages the lower end of the bar 39 and prevents movement of the bar downwardly out of the door sealing and locking position until the rocker 55 is released from the bar 39.

In order to trip the rocker 55 so that it is moved out of interlocking position with the bar 39, an interlock release 60 is provided. The interlock release 60 comprises a rocker arm 61 disposed between the door and the rocker 55 and having an intumed end 62 which engages an elongated slot 63 in the rocker. The arm 61 is mounted on a rotatable shaft 64 for rotation therewith. The shaft is rotatably mounted in the door and the outer end of the shaft is provided with an enlarged head 65 positioned externally of the door. The head 65 has a slot 66 for receiving the tip of a screwdriver for rotating the shaft 64 and thereby rocking the rocker 55 about its pivot 66 against the force of the biasing spring 58, thereby to remove the upper bent over end 59 from beneath the lower end of the bar 39.

When the lower end of the bar 39 is released, the biasing spring 44 drives the bar 39 downwardly to a position wherein the fingers 42 and 43 are released from the wedge fingers 32 and 34, respectively.

Also, in order to prevent closure of the switch while the door is open or before it is sealed, a door interlock 70 is provided. The door interlock 70 comprises a rocker 71 having a finger 71a, as best illustrated in FIG. 1, which is mounted on a shaft 72 extending parallel to the shaft 11. The rocker is secured to the shaft 72 for rotation therewith at its outer end. The shaft carries a slotted head 73 for rocking the shaft and thereby the rocker 71 to a released position from the exterior of the box, thereby providing an interlock release or defeater.

As is more fully described in the above patents, the rocker 71 is normally urged in a counterclockwise direction by the spring 74. The rocker has a surface which, in the open switch position of the switch-operating cam 18, with the bar 39 in door unsealing position, as in FIG. 4, obstructs a finger 76 of the cam 18, and prevents moving the handle 10 clockwise to closed switch position.

Upon moving the locking bar 39 to scaling position, the rocker 71 is rocked thereby against the force of the spring 74 into a position in which it removes the surface 75 from the path of the finger 76 thus permitting the cam 18 to be operated to close the switch.

If it is desired to open the door while the switch is closed, the rocker 55 is operated by the interlock release 60 to release the bar 39 whereupon the spring 44 causes the bar 39 to withdraw from the rocker 71 which, under the influence of the spring 74, then swings toward the cam 18. Thereupon the edge 77 of the rocker 71, if the switch in ON, engages the periphery of the cam operator thus holding the interlock in a position in which it cannot interfere with the opening of the switch by the handle 10. However, in this position of the rocker 71, the finger 71a is positioned to overlie the finger 33 of the door, and thus prevent opening of the door while the switch is ON even though the door is unsealed.

As the handle 10 is moved farther in the opening direction, the periphery of the cam operator passes out of engagement with the edge 77 of the rocker 71, but just before this happens one of the fingers of the cam 18, which is to open the switch, engages the edge 77 and holds the rocker in the same position until the cam snaps to open switch position and releases the rocker 71 so that it rocks to interlock position with the cam fingers 76 and prevents reclosure of the switch.

A stop rod 78 is mounted in the box in position to limit the movement of the cam 18 by its spring 26 in the opening direction after the cam has opened the switch.

To open the door with the switch ON, the shaft 72 is operated by inserting a screwdriver in the slot of the head 73 and rotating the shaft 72, thereby positioning the rocker 71 so that all of its surfaces are in inoperative position with respect to the cam 18, the cam operator l5 and the door fingers 33. Thus the door can be operated with the switch ON.

Once the bar 39 has been moved to efiect sealing of the door, the door cannot be opened whether the switch is opened or closed without operating the rocker 55 to defeat the sealing operation of the bar 39. If the switch is closed, then the rocker 55 and rocker 71 must both be released. To close the switch with the door open, ti is necessary to operate the interlock 70 to release the cam operator 15. The handle bearing plate 12 has a circumferentially extending slot 80 positioned so that when the switch is in OFF position, padlock hasps may be passed through the slot to prevent accidental closure by the handle 10. The handle carries a guard 81 which in the ON position of the switch prevents the insertion of the padlock hasps.

Thus normally the door must be closed and sealed before the switch can be turned on, and to do so it is only necessary while the switch is OFF, to close the door and swing the handle 10 so as to move the bar 39 to sealing position. When it is latched in this position, the switch can be turned OFF and ON Thus by the provision of the one-way ratchet connection between the operating handle 10 and the cam operator 15 of the switch-operating mechanism, a number of the parts of the prior patents are eliminated.

Having thus described my invention, 1 claim:

1. A switch enclosure comprising a box member having enclosing walls and a service opening at the front;

a door member hingedly connected to the box member for movement to open and closed positions relative to the opening;

switch-operating mechanism mounted in the box member for movement in opposite directions to ON and OFF positions, respectively;

an operating handle disposed exteriorly of the box member;

a rockable drive shaft connected to the handle and rockable thereby and drivingly connected to the switch-operating mechanism for driving the mechanism to said ON and OFF position, selectively;

a sealing gasket for the opening carried by at least one of the members;

a bar mounted in the box member for guided movement from a cover releasing starting position to a cover sealing position; and

cooperating-means on the inside of the door member and, when the door member is closed, engageable by the bar and operated thereby, when the bar is moved is toward sealing position, to draw the members into firm sealing engagement with the gasket and to hold the members in said sealing engagement so long as the bar remains in said sealing position;

characterized in that:

resilient biasing means are provided and bias the bar toward starting position;

releasable ratchet one-way drive means drivingly interconnect the rock shaft and bar so as to drive the bar, against the force of the resilient biasing means, to sealing and locking position when the handle is moved in a direction to drive the switch-operating mechanism a predetermined distance toward ON position, and to release the bar for return by the resilient biasing means upon continued movement of the handle in the same direction;

interlock means are carried by one of the members and are movable from a release to a latching position with respect to the bar wherein the interlock means latches the bar against return starting position; and

interlock biasing means bias the interlock means toward said latching position and are rendered operative to move the interlock means into said latching position by movement of the bar to sealing position.

2. The structure according to claim 1 wherein defeater means are connected to the interlock means and have a portion disposed exteriorly of the members and operable to move the interlock means to release the bar independently of the positions of the bar and operating handle.

3. The structure according to claim 1 wherein the releasable ratchet one-way drive means includes a driving detent connected to said drive shaft and drivable thereby along a predetermined path in a first direction away from a starting position upon rocking of the handle toward ON position, and in the reverse direction upon rocking of the handle in the opposite direction;

a driven detent connected to the bar and extending into the path of the driving lug; and

a one-way driving connecting means drivingly connecting the detents, as the driving detent moves along a portion of its path in the first direction, to drive the bar to sealing position, and then releasing the detents upon continued movement of the driving detent in said first direction.

4. The structure according to claim 3 wherein the one-way connection comprises connecting means on one detent movable into and out of said path and resiliently biased into the path, said last-mentioned means presenting an abrupt driving shoulder toward the other detent for engagement and driving thereby as the detents are moved in the direction for driving the bar to sealing position, and one of said detents being shaped so as to present a cam surface to the other detent for engagement by said other detent so as to move said connecting means out of said path against the force of its biasing means when the driving one of the detents is returned in the opposite direction from that for driving the bar to sealing position while the bar is in door releasing position.

5. The structure according to claim 4 wherein the one detent is a leaf spring having a connecting portion and having a free end portion diverging from the connecting portion, so as to extend into said path.

6. The structure according to claim 1 wherein the one-way ratchet means are so arranged as to drive the bar to sealing and interlocking position before the handle has been moved in the said direction sufficiently to drive the switch-operating mechanism to ON position; and

snap action means are provided and are connected to the switch-operating mechanism to drive the switch-operating mechanism to fully ON position after the handle has been moved a distance in said direction greater than said predetermined distance.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,629,536 Dated December 21, 1971 Inventor(s) Q Tadeusz J. Rye

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the title, 001 1, after "SWITCH-OPERATING" read --HAl\IDLE-- Col. 4, line 29, for "49" read --59-- C01. 5, line 3, for in" read --is-- Col. 5, line 32, for "ti" read --it-- Signed and sealed this 5th day of December 1972.

(SEAL) Attest:

ROBERT GOTTSCHALK EDWARD M.FLETCHER,JR.

Commissioner of Patents 7 Attesting Officer FORM USCOMM-DC 6C376-P69 U 5 GOVERNMENT PRINTING OFF'CE 959 O 365-33A UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,629,536 Dated December 21, 1971 Inventor(s) Tadeusz J. Rye

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the title, C01; 1, after "SWITCH-OPERATING" read -HANDLE-- Col. 4, line 29, for "49" read 59-- Col. 5, line 3, for "in" read --is-- Col. 5, line 32, for "ti" read --it--' Signed and sealed this 5th day of December 1972.

'(SEAL) Attest:

ROBERT GO'I'TSCHALK EDWARD M.FLETCHER,JR.

Commissioner of Patents Attesting Officer USCOMM-DC 6C376-P89 FORM PO-105O (10-69) n u 5 GOVERNMENT PRINTING orrlce was 0-356-334 

1. A switch enclosure comprising a box member having enclosing walls and a service opening at the front; a door member hingedly connected to the box member for movement to open and closed positions relative to the opening; switch-operating mechanism mounted in the box member for movement in opposite directions to ON and OFF positions, respectively; an operating handle disposed exteriorly of the box member; a rockable drive shaft connected to the handle and rockable thereby and drivingly connected to the switch-operating mechanism for driving the mechanism to said ON and OFF position, selectively; a sealing gasket for the opening carried by at least one of the members; a bar mounted in the box member for guided movement from a cover releasing starting position to a cover sealing position; and cooperating means on the inside of the door member and, when the door member is closed, engageable by the bar and operated thereby, when the bar is moved is toward sealing position, to draw the members into firm sealing engagement with the gasket and to hold the members in said sealing engagement so long as the bar remains in said sealing position; characterized in that: resilient biasing means are provided and bias the bar toward starting position; releasable ratchet one-way drive means drivingly interconnect the rock shaft and bar so as to drive the bar, against the force of the resilient biasing means, to sealing and locking position when the handle is moved in a direction to drive the switch-operating mechanism a predetermined distance toward ON position, and to release the bar for return by the resilient biasing means upon continued movement of the handle in the same direction; interlock means are carried by one of the members and are movable from a release to a latching position with respect to the bar wherein the interlock means latches the bar against return starting position; and interlock biasing means bias the interlock means toward said latching position and are rendered operative to move the interlock means into said latching position by movement of the bar to sealing position.
 2. The structure according to claim 1 wherein defeater means are connected to the interlock means and have a portion disposed exteriorly of the members and operable to move the interlock means to release the bar independently of the positions of the bar and operating handle.
 3. The structure according to claim 1 wherein the releasable ratchet one-way drive means includes a driving detent connected to said drive shaft and drivable thereby along a predetermined path in a first direction away from a starting position upon rocking of the handle toward ON position, and in the reverse direction upon rocking of the handle in the opposite direction; a driven detent connected to the bar and extending into the path of the driving lug; and a one-way driving connecting means drivingly connecting the detents, as the drivinG detent moves along a portion of its path in the first direction, to drive the bar to sealing position, and then releasing the detents upon continued movement of the driving detent in said first direction.
 4. The structure according to claim 3 wherein the one-way connection comprises connecting means on one detent movable into and out of said path and resiliently biased into the path, said last-mentioned means presenting an abrupt driving shoulder toward the other detent for engagement and driving thereby as the detents are moved in the direction for driving the bar to sealing position, and one of said detents being shaped so as to present a cam surface to the other detent for engagement by said other detent so as to move said connecting means out of said path against the force of its biasing means when the driving one of the detents is returned in the opposite direction from that for driving the bar to sealing position while the bar is in door releasing position.
 5. The structure according to claim 4 wherein the one detent is a leaf spring having a connecting portion and having a free end portion diverging from the connecting portion, so as to extend into said path.
 6. The structure according to claim 1 wherein the one-way ratchet means are so arranged as to drive the bar to sealing and interlocking position before the handle has been moved in the said direction sufficiently to drive the switch-operating mechanism to ON position; and snap action means are provided and are connected to the switch-operating mechanism to drive the switch-operating mechanism to fully ON position after the handle has been moved a distance in said direction greater than said predetermined distance. 